from datetime import datetime, timedelta
from typing import Any, Union, Optional
from jose import JWTError, jwt
from passlib.context import CryptContext
from fastapi import Depends, HTTPException, status
from fastapi.security import OAuth2PasswordBearer
from app.core.config import settings

pwd_context = CryptContext(schemes=["bcrypt"], deprecated="auto")
oauth2_scheme = OAuth2PasswordBearer(tokenUrl="/api/v1/auth/login")

def verify_password(plain_password: str, hashed_password: str) -> bool:
    return pwd_context.verify(plain_password, hashed_password)

def get_password_hash(password: str) -> str:
    return pwd_context.hash(password)

def create_access_token(
    subject: Union[str, Any], expires_delta: timedelta = None
) -> str:
    if expires_delta:
        expire = datetime.utcnow() + expires_delta
    else:
        expire = datetime.utcnow() + timedelta(
            minutes=settings.ACCESS_TOKEN_EXPIRE_MINUTES
        )
    to_encode = {"exp": expire, "sub": str(subject)}
    encoded_jwt = jwt.encode(
        to_encode, settings.SECRET_KEY, algorithm=settings.ALGORITHM
    )
    return encoded_jwt

def decode_access_token(token: str) -> Optional[dict]:
    try:
        payload = jwt.decode(
            token,
            settings.SECRET_KEY,
            algorithms=[settings.ALGORITHM]
        )
        return payload
    except JWTError:
        return None

async def get_current_user_id(token: str = Depends(oauth2_scheme)) -> str:
    """从 token 中获取当前用户 ID"""
    credentials_exception = HTTPException(
        status_code=status.HTTP_401_UNAUTHORIZED,
        detail="无效的认证凭据",
        headers={"WWW-Authenticate": "Bearer"},
    )
    try:
        payload = jwt.decode(
            token, settings.SECRET_KEY, algorithms=[settings.ALGORITHM]
        )
        user_id: str = payload.get("sub")
        if user_id is None:
            raise credentials_exception
        return user_id
    except jwt.JWTError:
        raise credentials_exception 